A Mexican gray wolf snuggles with two pups at the Sedgwick County Zoo. At one time, gray wolves were among the most widely distributed mammals on Earth. However, by the early 1900s, unchecked trapping, poisoning, and hunting of these highly intelligent predators drove the species to the brink of extinction.

(Text adapted from and photograph shot on assignment for, but not published in, "Return of the Gray Wolf," May 1998, National Geographic magazine)